Judah Levine, 3070L14 1http://physics.colorado.edu/phys3070http://physics.colorado.edu/phys3070Judah LevineJudah LevineJILA SJILA [email protected]@colorado.edu303 492303 492--7785 (27785 (2--7785)7785)M,F 11M,F 11--Noon, W 1Noon, W 1--3 pm3 pmalso by appointmentalso by appointmentJudah Levine, 3070L14 2Refrigerator Energy FlowRefrigerator Energy FlowTHRefrigerator transfers heatFrom the inside to the room.Room warms up by QHRefrigerator cools off by QLQH=QL+W > QLTLQHWQLWattshrBTUWQeerL/==Judah Levine, 3070L14 3Energy Efficiency RatioEnergy Efficiency RatioWattshrBTUWQeerL/==Suppose eer=13 (a high-efficiency value).Typical room air conditioner removes12,000 BTU/hr (“1 ton” unit)Input power= 12,000/13= 923 WattsEnergy used in 1 day= 923Watts×24hours= 22.2kWh$2.22/day @ $0.10/kwhIs this a lot or a little?Judah Levine, 3070L14 4Clicker question ..Clicker question ..A: This is a lotB: Get a life, this is a littleJudah Levine, 3070L14 5Energy Efficiency RatioEnergy Efficiency RatioWattshrBTUstoreeerWQratioeerL/)()(==Suppose eer(store)=13How much energy (in joules) does it take to move 10 joules of energy from the cooler region to the warmer region?A: 1.31 joulesB: 2.62 joulesC: 10.2 joulesD: 13.3 joulesJudah Levine, 3070L14 6Energy Efficiency RatioEnergy Efficiency RatioWattshrBTUstoreeer/13)( =joulesjouleseerQWWQratioenergyhrBTUwattWattshrBTUeerLL62.281.31081.381.3/41.31/13======×≈Answer is BJudah Levine, 3070L14 7Heat Pump Energy FlowHeat Pump Energy FlowTH1>=>+=WQCOPWQWQHLHRoom warms upby QHTLQHWQLExtract energy QLfrom the great outdoorsJudah Levine, 3070L14 8RefrigeratorRefrigeratorEasy to liquefyEvaporates at cold tempCool (inside) Warm (outside)Gas flowLiquidGasLiquid flowCompressorGas to liquidQLQHExpansionvalveJudah Levine, 3070L14 9RefrigerantsRefrigerantsFCFluorine/Chlorine replacehydrogen in methanestructureClClFFreon 12Judah Levine, 3070L14 10RefrigerantsRefrigerantsFHFCClClFFreon 12CF2Cl2FFCC FHHFC-134CHF2– CHF2Chlorine primarily responsible for ozone depletionJudah Levine, 3070L14 11Electric power generationElectric power generationNSCoil ACoil BCoil C3-phase“Delta”O3O2 O1Judah Levine, 3070L14 1233--phase Delta transmissionphase Delta transmissionJudah Levine, 3070L14 13Electrical circuit parametersElectrical circuit parametersohmsinrrilossenergywattssecondjoulesecondchargechargejouleviampsVoltssecondchargeiampscurrentchargejoulesvVolts2===×==×=====Energy transfer/work requires motion of chargesJudah Levine, 3070L14 14Transmission efficiencyTransmission efficiency%92130012001001101101201200120120022====×=======×=inputoutputefficiencywattslossohmrampsivoltsvwattsprilossontransmissiivdeliveredpowerJudah Levine, 3070L14 15Transmission efficiencyTransmission efficiency=====×=efficiencyohmrvoltsvwattsprilossontransmissiivdeliveredpower124012002A: 88%B: 92%C: 96%D: 98%E: 100%Judah Levine, 3070L14 16Transmission efficiencyTransmission efficiency%98122512002515152401200240120022====×=======×=inputoutputefficiencywattslossohmrampsivoltsvwattsprilossontransmissiivdeliveredpowerAnswer= DJudah Levine, 3070L14 17High Voltage transmissionHigh Voltage transmissionJudah Levine, 3070L14 18StepStep--down transformerdown transformerStep up andStep downpossible only withalternating currentsystemsJudah Levine, 3070L14 19Alternating vs. Direct currentAlternating vs. Direct currentExtra credit study:“War of the currents”Thomas Edison vs. Nikola Tesla and George Westinghouse1 paragraph min, 1 page max by Wednesday, 8 March, 9 amJudah Levine, 3070L14 20Light as a waveLight as a waveWavelength= distance between wave crests1 micron=10-6m1 nano-meter=1nm=10-9mX-rays, gamma rays, …< 400 nm ultra-violet400 nm blue500 nm green670 nm red> 700 nm near infrared>1000 nm = 1micron= far infraredcm – km: microwaves, TV, FM, AM …Judah Levine, 3070L14 21A Black BodyA Black BodyAbsorbs all radiation that falls on itKinetic energy of atoms radiateselectromagnetic energyWhat is spectrum of the
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